Researchers have found a link between restless legs syndrome and future heart disease in women, but the new findings contradict earlier studies, and one expert said it's too early to be alarmed.
"The evidence to date is not really convincing enough to go out to the public and say, 'If you have restless legs, you should be concerned about heart disease,'" said Dr Tobias Kurth, a director of research at the French National Institute of Health and Medical Research in Bordeaux.
Restless legs syndrome (RLS) is a recognised neurological disorder, but because the symptoms are so vague and may be fleeting, it is unclear when it should be considered a disease. As a result, estimates of how common the condition is have ranged widely - from just a few percent to nearly a quarter of all people.
The new findings, published in Circulation, are based on data from the massive Nurses' Health Study. Researchers tracked more than 70 000 women from 2002, when none of them had heart disease, until 2008. Overall, there was no link between RLS and heart disease. But women who had been diagnosed with the disorder at least three years before the study began were at higher risk.
Women who died from heart disease
The rate of death from heart disease was 3.5% per decade among this group, compared to 1.7% per decade among women without RLS. They were also more likely to have non-fatal heart attacks.
Dr Xiang Gao, who led the work, said the study doesn't prove that RLS causes heart disease, even though he and his colleagues tried to rule out several possible explanations, such as differences in sleep duration and physical activity. "Because this an observational study there are still some unknown factors that could affect the association," cautioned Dr Gao, from Brigham and Women's Hospital in Boston.
Previous research has supported the link between RLS and heart disease, but it hasn't been able to tease out which came first. The only two studies to look at that question did not find any association between the neurological problem and later heart problems, although they didn't consider the duration of RLS.
"Overall to me that means there is no consistent evidence that restless legs per se should be considered as a risk factor for coronary heart disease," said Dr Kurth, who led one of those studies. While he acknowledged that some people can have severe RLS that warrants treatment, he said that in other cases the problem may be mild or resolve on its own.
"Is this syndrome a disease in everybody? That is the question for me that is still unclear," Dr Kurth told Reuters Health.
(Reuters Health, Frederik Joelving, September 2012)
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